Today, fluoride is a well-known cavity fighter. However, it was completely unknown in the early 20th century. A young dental school graduate made an interesting observation in 1901. This began the discovery of fluoride’s cavity fighting benefits.

Brown teeth discovery in Colorado

In 1901, Frederick McKay moved to Colorado to open his own dental practice. He observed that many of the Colorado Springs locals had brown stains on their teeth. McKay searched for the cause. A few tears later, a dental researcher accepted McKay’s invitation and arrived in Colorado to help with the investigation. The men worked together for six years. They found that about 90% of the children native to Colorado Springs had brown stains. The men named the condition “mottled teeth.” They were surprised to discover that mottled teeth were resistant to tooth decay.

More findings of mottled teeth

In 1923, McKay went from Colorado Springs to Oakley, Idaho. He went to investigate new reports of tooth mottling there. Families reported that the stains appeared not long after Oakley built a new water pipeline to a warm spring. McKay advised town leaders to stop using the pipeline and use a nearby spring instead. The town did so, and the brown stains disappeared within a few years. This was the first indication that something in the water was causing mottled teeth.

McKay then went to Bauxite, Arkansas, a town owned by an aluminum plant. The people Bauxite had mottled teeth but those in nearby towns did not. McKay asked the town to study the water. The plant’s chief chemist analyzed the water and discovered high levels of fluoride there. He wrote a letter informing McKay of the findings and asked McKay to test samples from the other areas.

Enamel Fluorosis linked to fluoride

The National Institute of Health (NIH) studied fluoride and enamel fluorosis (formerly referred to as teeth mottling) in the 1930s, after McKay reported his findings. The NIH found that fluoride levels up to 1.0 ppm could not cause enamel fluorosis, the brown stains. Researchers looked again at McKay’s findings of anti-cavity effects and determined that low levels of fluoride would significantly improve oral health by helping to prevent tooth decay.

We know so much more about fluoride today and understand its cavity fighting ability. Many areas add it to water sources. Most toothpastes, rinses and professional treatments also contain fluoride.